In the current version of SWPCB I can't import the original PCBDOC file coming out from Altium Designer 17.x due to the file type not being recognized. This is however not a problem, saving in 5.0 version is easy. But... When exporting the 3D Step models they become extruded objects when opened/imported into SWPCB.
Some of the 3D Models look kind of strange also, they go straight through the PCB. (Stand-off height issues(?))